rtla: Fix parse_cpu_set() bug introduced by strtoi()

rtla: Fix parse_cpu_set() bug introduced by strtoi()

The patch 'Replace atoi() with a robust strtoi()' introduced a bug
in parse_cpu_set(), which relies on partial parsing of the input string.

The function parses CPU specifications like '0-3,5' by incrementing
a pointer through the string. strtoi() rejects strings with trailing
characters, causing parse_cpu_set() to fail on any CPU list with
multiple entries.

Restore the original use of atoi() in parse_cpu_set().

Fixes: 7e9dfccf8f11 ("rtla: Replace atoi() with a robust strtoi()")
Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20260112192642.212848-2-costa.shul@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>